Pulsation damping device for a pump

ABSTRACT

According to the present invention, a device body casing  17  has a liquid chamber  20   a  for temporarily storing a liquid to be transported by a pump, a gas chamber  20   b,  and an extendably and contractibly deformable pulsation suppression diaphragm  18,  which separate them. The device body casing  17  having an aperture  27  so as to communicate with gas chamber  20   b,  is detachably engaged with a valve case  23.  The valve case  23  is provided with an automatic gas supply valve mechanism  33  and an automatic gas exhaust valve mechanism  34,  which restrict the amount of the extendable and contractible deformation of the pulsation suppression diaphragm  18  within the predetermined range, so that a liquid pressure inside the liquid chamber  20   a  and an atmospheric pressure inside the gas chamber  20   b  may balance each other when the discharge pressure of the pump is fluctuated. The automatic gas exhaust valve mechanism  34  is provided with a gas exhaust port  32,  a gas exhaust valve element  43,  and a slider  48.  The gas exhaust port  32  exhausts the gas from the gas chamber  20   b  to the outside, when the gas sealing pressure inside the gas chamber  20   b  is decreased. The gas exhaust valve element  43  usually makes the gas exhaust port  32  close. The slider  48  is operated so that the gas exhaust valve element  43  may usually make the gas exhaust port  32  open, when the pulsation suppression diaphragm  18  is moved in a direction of reducing the liquid chamber  20   a  so as to exceed the predetermined stroke. The gas exhaust valve element  43  is disposed on a tip of the gas exhaust valve rod  45.  A rear end of the gas exhaust valve rod  45  is slidably inserted in the slider  48.  The gas exhaust valve rod  45  is loosely inserted in a through hole  46  of the spring receiving member  47  fixed to the inside of the gas exhaust chamber  42  of the valve case  23.  On the gas exhaust rod  45,  a spring  49  for a closing state is disposed between the gas exhaust valve element  43  and the spring receiving member  47,  and a spring  50  for an opening state is disposed between the spring receiving member  47  and the slider  48.

TECHNICAL FIELD

The present invention relates to a pulsation damping device for a pump,which damps a pulsation caused by fluctuations of a flow rate and apressure of a liquid to be transported such as processing chemicalliquids used in a semiconductor production, via a piping system forsupplying the transported liquid to each element by a reciprocal pump.

BACKGROUND ART

A pulsation damping device for a pump of this type, has been disclosedin, for example, Japanese Patent Publication Laying-open Nos. 6-17752and 8-159016.

The pulsation damping device for a pump shown in Japanese PatentPublication Laying-open No. 6-17752 is illustrated in FIG. 4. Theproposed pulsation damping device has a hermetical device body casing60, a liquid chamber 61 a disposed inside the device body casing 60, forfunctioning as a storage of the liquid, which sucks and storestemporarily the transported liquid by the reciprocal pump, anddischarges it, and a gas chamber 61 b disposed inside the device bodycasing 60, which is separated from the liquid chamber 61 a via anextendable and contractible diaphragm 62 for suppressing pulsation, soas to seal a gas, whereby the pulsation suppression diaphragm isextendably and contractibly deformed by pulsation of the dischargepressure of the pump. The proposed device has the above configuration,thereby making it possible to damp the pulsation by change of thecapacity of the liquid chamber 61 a.

When the discharge pressure of the reciprocal pump is fluctuated, it isnecessary to keep the deformation amount of the pulsation suppressiondiaphragm 62 caused by extension and contraction, within a predeterminedrange, so that the liquid pressure inside the liquid chamber 61 a and anatmospheric pressure inside the gas chamber 61 b may balance each other.Therefore, the device as shown in FIG. 4 adopts the followingconfiguration. The device body casing 60 is provided with an automaticgas supply valve mechanism 63 and an automatic gas exhaust valvemechanism 64. When the pulsation suppression diaphragm 62 is extendablydeformed by the fluctuation of the liquid pressure inside the liquidchamber 61 a, in the direction wherein the capacity of the liquidchamber is increased so as to be above a standard value S, therebyexceeding a predetermined range A, the diaphragm 62 for suppressingpulsation opens the gas supply port 66 via the valve press rod 65 of theautomatic gas supply valve mechanism 63, thereby adjusting the gassealing pressure of the gas chamber 61 b so as to be increased.Moreover, when the diaphragm 62 for suppressing pulsation iscontractibly deformed in the direction wherein the capacity of theliquid chamber is decreased so as to be below the standard value S,thereby exceeding a predetermined range B, the automatic gas exhaustvalve mechanism 64 opens the gas exhaust port 68 by means of a slider 67abutting against an closed end portion 62 a of the diaphragm 62 forsuppressing pulsation. As a result, the gas inside the gas chamber 61 bis exhausted and adjusted so as to decrease the gas sealing pressure.

On the other hand, a pulsation suppression device for a pump disclosedin Japanese Patent Publication Laying-open No. 8-159016 is shown in FIG.5A. A switching valve mechanism for switching between gas supply and gasexhaust is shown in FIG. 5B. The proposed device adopts a gas chamberinternal pressure adjusting valve mechanism for restricting the changeof the capacity of the liquid chamber 61 a disposed in the same way asthe liquid chamber 61 a disclosed in Japanese Patent PublicationLaying-open No. 6-17752 so as to be within the predetermined range ofthe displacement of the capacity. In the mechanism, the switching valvemechanism for switching between gas supply and gas exhaust having anoperating rod 69 and a slide valve element 71 is protrusively fitted onan outer side of the device body casing 60. The operating rod 69 isoperated according to a displacement of the closed end side 62 a of thediaphragm 62 for suppressing pulsation. The slide valve element 71 makesa gas supply and exhaust passage 70 for using both gas supply and gasexhaust, alternatively connect to the gas supply port 66 and the gasexhaust port 68. The gas supply and exhaust passage 70 is operated bythe operating rod 69 so as to communicate with the gas chamber 61 b. Thevalve mechanism has the structure as below. The valve mechanism makesthe gas supply port 66 connect to the gas supply and exhaust passage 70when the capacity of the liquid chamber 61 a is increased so as to beabove the predetermined range. The valve mechanism makes the gas exhaustport 68 connect to the gas supply and exhaust passage 70 when thecapacity of the liquid chamber 61 a is decreased so as to be below thepredetermined range. It has a cylindrical casing 72 provided with thegas supply and exhaust passage 70 which communicates with the gas supplyport 66, the gas exhaust part 68, and the gas chamber 61 b, and theslide valve element 71 which is coaxially coupled to the operating rod69 so as to be slidably and displaceably engaged with the inside of thecylinder 73 housed inside the cylindrical casing 72.

Among the two prior arts mentioned above, the device disclosed in theformer one, i.e., Japanese Patent Publication Laying-open No. 6-17752,has a structure wherein the automatic gas supply valve mechanism 63 andthe automatic gas exhaust valve mechanism 64 are integrally formed withthe lower side member 60 a as an element of the device body casing 60.Therefore, when either of valve mechanisms 63, 64 is damaged ordestroyed, it is necessary to disassemble and repair the device body orreplace a whole of the body. This requires much labor, thereby resultingin disadvantage in maintenance and cost. Moreover, the gas exhaust port68 of the automatic gas exhaust valve mechanism 64 is structurallyconfined by a phenomenon wherein a gas exhaust valve element 75 dropsowing to its weight. Therefore, the closing action is unstable, and thedevice must be installed so as to keep vertical arrangement relationshipbetween the gas exhaust valve element 75 and the gas exhaust port 68.For example, it cannot be allowed that the device is installed so thatthe gas exhaust valve element 75 may be horizontally arranged. As aresult, kinds of the device are restricted.

The switching valve mechanism for switching between gas supply and gasexhaust disclosed in Japanese Patent Publication Laying-open No.8-159016, i.e., the latter one, adopts a configuration wherein one valveis used for both the gas supply and the gas exhaust. Therefore, it isnot necessary to disassemble the device body. It is efficient only todisassemble the switching valve mechanism and repair or replace it. Incase of closing the gas supply port 66 and the gas exhaust port 68, thisdoes not structurally rely on the weight of the gas exhaust valveelement 75, which is different from the former one, thereby making itpossible to overcome the problem in the former one. However, on theother hand, it has disadvantages as below. The structure of theswitching valve is very complicated, the seal of the slide valve element71 is so difficult, and it protrudes to the outside of the device bodycasing 60, whereby a whole of the device is bulky and large-sized.

The present invention has been conducted in view of the above mentionedcircumstances. Especially, an object of the present invention is toprovide a pulsation damping device for a pump, which can be installed ineither vertical or horizontal style by improving the gas exhaust valvemechanism. This can diversify kinds of the device.

Moreover, another object of the present invention is to provide thepulsation damping device for a pump whose structure is simple, which canbe economically produced, and wherein it is easy to maintain the gassupply and exhaust valves.

DISCLOSURE OF THE INVENTION

A pulsation damping device for a pump according to the present inventioncomprises:

a hermetical device body casing having

a liquid chamber for supplying a transported liquid to be transported bya reciprocal pump, from an inflow passage, temporarily storing thetransported liquid, and discharging it from an outflow passage, and

a gas chamber to be filled with a gas for suppressing pulsation,

a pulsation suppression diaphragm for suppressing pulsation, whichpartitions an interior of said device body casing into the liquidchamber and the gas chamber, and which can freely reciprocate accordingto a balance between each fluctuation of flowing amount and pressure ofthe transported liquid and a gas sealing pressure inside the gaschamber,

a gas pressure supply means for supplying the gas chamber with a gaspressure,

a gas supply port for guiding the gas pressure from the gas pressuresupply means to an inside of the gas chamber when the gas sealingpressure inside the gas chamber is raised,

a gas exhaust port for exhausting the gas from the gas chamber to theoutside thereof when the gas sealing pressure inside the gas chamber islowered,

an automatic gas supply valve mechanism for usually closing the gassupply port,

an automatic gas exhaust valve mechanism for usually closing the gasexhaust port,

a valve press rod disposed between the automatic gas supply valvemechanism and the pulsation suppression diaphragm, which is actuated soas to open usually the gas supply port when the pulsation suppressiondiaphragm is moved beyond a predetermined stroke in the direction ofexpanding the liquid chamber, and

a slider disposed between the automatic gas exhaust valve mechanism andthe pulsation suppression diaphragm, which is actuated so as to openusually the gas exhaust port when the pulsation suppression diaphragm ismoved beyond a predetermined stroke in the direction of reducing theliquid chamber. Moreover, in the pulsation damping device for a pumphaving the above-mentioned structure, the automatic gas exhaust valvemechanism includes:

a gas exhaust valve rod loosely inserted in a through hole of a springreceiving member fixed in the device body casing, so as to form a space,

a gas exhaust valve element disposed on a tip of the gas exhaust valverod, which can freely touch or separate from a valve seat of the gasexhaust port, and

the slider arranged at an rear end of the gas exhaust valve rod so as tobe slidable in an axial direction of the valve,

a spring for a closing state is disposed between the gas exhaust valveelement and the spring receiving member, and

a spring for an opening state is disposed between the gas exhaust valveelement and the slider.

According to the pulsation damping device having the above structure,when the capacity of the liquid chamber is increased so as to exceed thepredetermined range by means of fluctuation of the discharge pressure inthe reciprocal pump, the automatic gas supply valve mechanism makes thegas supply to the inside of the gas chamber, thereby raising the sealingpressure. This restricts extendable deformation of the pulsationsuppression diaphragm. When the capacity of the liquid chamber isdecreased so as to exceed the predetermined range, the automatic gasexhaust valve mechanism makes gas exhaust from the inside of the gaschamber, thereby lowering the sealing pressure. This restricts thecontractible deformation of the pulsation suppression diaphragm. Inspite of the fluctuation of the discharge pressure of the reciprocalpump, the extendable and contractible deformation amount of thepulsation suppression diaphragm is restricted within a predeterminedrange, thereby keeping the range of the pulsation small. Furthermore, inthe automatic gas exhaust valve mechanism, the spring for a closingstate functions so that the gas exhaust valve element may closecompulsorily the gas exhaust port. Therefore, the gas exhaust port canbe stably and surely closed. Moreover, even if the device is installedin either vertical style or horizontal style so that the gas exhaustvalve element may be vertically or horizontally arranged, it neveradversely affects the closing action of the gas exhaust port.

According to the pulsation damping device of a pump according to anotherinvention, the device body casing is provided with an aperture forcommunicating with the gas chamber, and a valve case is detachablyengaged with an inside of the aperture,

the valve case is provided with the gas supply port, the gas exhaustport, the automatic gas supply valve mechanism, the valve press rod, theslider, the gas exhaust valve element of the automatic gas exhaust valvemechanism, the exhaust valve rod, the spring receiving member, thespring for a closing state, and the spring for an opening state.

In the pulsation damping device of a pump having the above structure,even if either the automatic gas supply valve mechanism or the automaticgas exhaust valve mechanism is damaged or destroyed, it can be easilyrepaired or replaced by pulling out only the valve case from theaperture. In other words, it has an advantage in maintenance aspect.Furthermore, the automatic gas supply valve mechanism and the automaticgas exhaust valve mechanism are independently disposed inside one valvecase, so as to be parallel with each other. Thus, the structure of thevalve is simple and it can be economically produced. The valve case isengaged with an inside of the aperture so as to be housed in a compactstate, without protruding outwardly from the device body casing.

Additionally, according to the pulsation damping device for a pumpaccording to a still another invention, the device body casing isintegrally provided with an air-driving type reciprocal pump, theair-driving type reciprocal pump includes

a diaphragm for a pump, which can be extendably and contractiblydeformed in an extending and contracting direction of the pulsationsuppression diaphragm,

an air cylinder portion for driving the diaphragm for a pump so as to beextendably and contractibly deformed, and

a pump working chamber disposed inside the diaphragm for a pump, thepump working chamber having suction and discharge check valves forsucking and discharging the transported liquid, the check valves beingalternately opened and closed in accordance with extendable andcontractible deformation of the diaphragm for a pump, and

the transported liquid discharged from the pump working chamber via adischarge check valve is fed to the liquid chamber.

According to the pulsation damping device for a pump having the abovestructure, when the diaphragm for a pump is moved so as to be extendablyand contractibly deformed via the air cylinder portion, the suctioncheck valve 16 a and the discharge check valve 16 b inside the pumpworking chamber are alternately opened and closed. As a result, suctionof the transported liquid from the inflow passage to the pump workingchamber and discharge of it from the inside of the pump working chamberto the outflow passage are repeated, thereby performing thepredetermined pump action. At this time, the transported liquiddischarged from the pump working chamber through the discharge checkvalve is discharged to the outflow passage through the liquid chamber ofthe pulsation damping device. At this time, in a peak of the pulsationof the discharge pressure of the discharged liquid, the pulsationsuppression diaphragm is moved in the direction of increasing thecapacity of the liquid chamber, so as to absorb the pressure. In avalley of the pulsation, the pulsation suppression diaphragm is moved ina direction wherein the capacity of the liquid chamber is decreased, thepressure of the discharged liquid is raised so as to absorb thepulsation, thereby making it possible to discharge continuously andsmoothly the transported liquid without pulsation. The reciprocal pumpis integrally formed with the pulsation damping device. In other words,it does not require an external piping for connecting therebetween.Additionally, this can reduce costs, downsize a whole of the device, andattain reduction of the installation space. The external piping can beomitted. Consequently, there is no fear wherein the piping is brokenthereby causing leakage of the liquid, even if it has been used for along time. Furthermore, loss of the pressure is extremely small. Thisallows the capacity of the pump to be small, and makes the pump itselfcompact, thereby making it possible to minimize an occupied area forinstalling the pump.

In addition, according to the pulsation damping device for a pumpaccording to a further another invention, a stopper is disposed on anend on a side of the gas chamber of the valve case, and the stopperrestricts further movement of the pulsation suppression diaphragm whenthe pulsation suppression diaphragm moves in the direction of expandingthe liquid chamber so as to be beyond a predetermined stroke and thevalve press rod is actuated.

According to the pulsation damping device for a pump having theabove-mentioned structure, the excessive extendable deformation of thepulsation suppression diaphragm can be restricted, thereby preventingthe damage of the pulsation suppression diaphragm.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal sectional front view of a whole of a pulsationdamping device for a pump according to the present invention.

FIG. 2 is an enlarged longitudinal sectional front view of an automaticgas supply valve mechanism and an automatic gas exhaust valve mechanismof the same pump.

FIG. 3 is a longitudinal sectional front view of a whole of thepulsation damping device for a pump according to the another embodiment.

FIG. 4 is a longitudinal sectional front view of a whole of a pulsationdamping device for a pump according to a prior art.

FIG. 5A is a longitudinal sectional front view of a whole of a pulsationdamping device for a pump according to another prior art.

FIG. 5B is an enlarged longitudinal sectional front view of a switchingvalve mechanism for switching between gas supply and gas exhaust, of thepump of FIG. 5A.

BEST MODES FOR CARRYING OUT THE INVENTION

FIG. 1 is a whole longitudinal sectional front view of a pulsationdamping device for a pump in case of applying the pulsation dampingdevice to an air driving type bellows pump for semiconductor producingdevice. FIG. 2 is an enlarging longitudinal sectional front view of aset of an automatic gas exhaust valve mechanism and an automatic gassupply valve mechanism. In FIG. 1, 1 designates a partition wall of adevice body having an inflow passage 2 and an outflow passage 3 of aliquid to be transported by a pump, a reciprocal pump 4 and a pulsationdamping device 5 which are opposed to each other, are disposed on bothsides of the partition wall 1 so as to be integrated with the partitionwall 1.

A bottomed cylindrical pump casing 6 is connectedly disposed on a sideof the partition wall 1. Inside the pump casing 6, a bottomedcylindrical diaphragm 7 for a pump, being a bellows or a diaphragm,which is extendably and contractibly deformed is (i.e., shown as abellows in this figure) disposed along the axial direction of thecylindrical portion. An opening peripheral portion 7 a of the diaphragm7 for a pump is hermetically pressed against a side surface of thepartition wall 1 and fixed thereto by an annular fixing plate 8.Therefore, an inside space of the pump casing 6 is hermeticallypartitioned into a pump working chamber 9 a inside the diaphragm 7 for apump and a pump operating chamber 9 b outside the diaphragm 7 for apump.

A cylindrical body 12 is fixed to an outside of a bottom wall 6 a of thepump casing 6. The cylindrical body 12 houses slidably a piston 11fixedly connected to a closed end member 7 b of the diaphragm 7 for apump, via a coupling member 10. An air cylinder portion 14 is disposedoutside the pump casing 6. Through air holes 13 a, 13 b formed on thecylindrical body 12 and the bottom wall 6 a of the pump casing 6,pressurized air fed from a pressurized air feeding device such as acompressor (not shown) is supplied to an inside of the cylindrical body12 or the pump operating chamber 9 b. As a result, the air cylinderportion 14 drives the diaphragm 7 for a pump so as to be extendably andcontractibly deformed. The air cylinder portion 14 is provided withadjacent sensors 25 a, 25 b. On the other hand, the piston 11 isprovided with a sensor detecting plate 26. The sensor detecting plate 26alternately approaches 25 a and 25 b in accordance with reciprocation ofthe piston 11, whereby supply of the pressurized air fed from thepressurized air feeding device to the inside of the cylindrical body 12and supply thereof from the pressurized air feeding device to the pumpoperating chamber 9 b are automatically switched.

Moreover, a sucking mouth 15 a and a discharging mouth 15 b formed so asto open each mouth to the pump working chamber 9 a respectivelycommunicate with the inflow passage 2 and outflow passage 3. The suckingmouth 15 a and the discharging mouth 15 b are respectively provided witha suction check valve 16 a and a discharge check valve 16 b. The checkvalves are alternately opened and closed in accordance with extendableand contractible deformation caused by driving the diaphragm 7 for apump. The pump 4 comprises the above elements.

On the other hand, a bottomed cylindrical device body casing 17 isdisposed on another side of the partition wall 1 so as to be coaxialwith the pump casing 6. Also, a bottomed cylindrical pulsationsuppression diaphragm 18 for suppressing pulsation (shown as the bellowsin this figure) is disposed inside the device body casing 17, so as tobe opposed to the diaphragm 7 for a pump in the pump 4. The pulsationsuppression diaphragm 18 is a bellows or diaphragm which is extendablyand contractibly deformable along the axial direction of the cylindricalportion. An opening peripheral edge 18 a of the pulsation suppressiondiaphragm 18 is hermetically and pressingly fixed to another sidesurface of the partition wall 1 by an annular fixing plate 19, wherebythe inside space of the device body casing 17 is partitioned into aliquid chamber 20 a and a gas chamber 20 b. The liquid chamber 20 a isfor temporarily storing a liquid to be discharged via the dischargecheck valve 16 b and a communication passage 21 formed by piercing thethickness of the partition wall 1, and the gas chamber 20 b is filledwith an air for decreasing pulsation.

By the above-mentioned elements, the pulsation damping device 5 isconfigured, wherein the pulsation caused by a discharging pressure of aliquid to be discharged from the pump working chamber 9 a is absorbedand damped by a change of capacity of the liquid chamber 20 a inaccordance with the extendable and contractible deformation of thepulsation suppression diaphragm 18.

An aperture 27 is formed in the neighborhood of the center of the outersurface of a bottom wall 17 a of the device body casing 17. A valve case23 with a flange 23 a is engaged with an inside of the aperture 27, andthe flange 23 a is pressingly fixed to the outside of the bottom wall 17a via bolt 24 or the like, so as to be detachable.

As shown in FIG. 2, the valve case 23 is provided with a gas supply port31 and a gas exhaust port 32 which are parallel with each other. The gassupply port 31 has an automatic gas supply valve mechanism 33 forraising a sealing pressure inside the gas chamber 20 b by supplying theair pressurized above the maximum pressure value of the transportedliquid to the gas chamber 20 b when the capacity of the liquid chamber20 a exceeds a predetermined range so as to be increased. The gasexhaust port 32 is provided with an automatic gas exhaust valvemechanism 34 for lowering a sealing pressure inside the gas chamber 20 bwhen a capacity of the liquid chamber 20 a exceeds a predetermined rangeso as to be decreased.

The automatic gas supply valve mechanism 33 includes a gas supply valvechamber 35 formed on the valve case 23 so as to communicate with the gassupply port 31, a gas supply valve element 36 for opening and closingthe gas supply port 31, which is slidable along the axis inside the gassupply valve chamber 35, a spring 37 for usually urging the gas supplyvalve element 36 to a close position, and a valve seat 38 of the gassupply valve element 36 in the inner end portion thereof. Furthermore,the automatic gas supply valve mechanism 33 includes a through hole 39for making the gas supply chamber 35 communicate with the gas chamber 20b, a guide member 40 screwed and fixed on the valve case 23, and a valvepress rod 41 slidably inserted in the through hole 39 of the guidemember 40. Under the condition wherein the pressure of liquid inside theliquid chamber 20 a is set at an average pressure, and the pulsationsuppression diaphragm 18 is located in a standard position S, the gassupply valve element 36 is closely fitted to the valve seat 38 of theguide member 40, so as to close the gas supply port 31. Moreover, underthe condition, the end portion 41 a facing the inside of the gas chamber20 b of the valve press rod 41 is distant from a closed end portion 18 bof the pulsation suppression diaphragm 18, so as to keep the space of astroke A.

The automatic gas exhaust valve mechanism 34 includes a gas exhaustvalve chamber 42 formed on the valve case 23 so as to communicate withthe gas exhaust port 32, a gas exhaust valve element 43 for opening andclosing the gas exhaust port 32, which is slidable along the axis insidethe gas exhaust valve chamber 42, a gas exhaust valve rod 45 having thegas exhaust valve element 43 on the front end thereof and a flangeportion 44 on the rear end thereof respectively, a spring receivingmember 47 having a through hole 46, which is screwingly fixed to theinside of the valve chamber 42 and in which the gas exhaust valve rod 45is inserted, a cylindrical slider 48 in which a rear end of the gasexhaust valve rod 45 is slidably inserted, and which prevents the gasexhaust valve rod 45 from slipping off, a spring 49 for a closing state,disposed between the gas exhaust valve element 43 and the springreceiving member 47, and a spring 50 for an opening state, disposedbetween the spring receiving member 47 and an closed end portion 48 a ofthe slider 48. A internal diameter of the through hole 46 of the springreceiving member 47 is greater than the axial diameter of the gasexhaust valve rod 45. Through a space 51 formed therebetween, the gasexhaust valve chamber 42 communicates with the gas chamber 20 b. Underthe condition wherein the pulsation suppression diaphragm 18 is locatedin a standard position S, the gas exhaust valve element 43 closes thegas exhaust port 32, and the flange portion 44 of the rear end of thegas exhaust valve rod 45 is apart from the inside of the closed endportion 48 a of the slider 48, so as to keep the space of a stroke B.)

The end on a side of the diaphragm, in the valve case 23, is extended ina direction of the inside of the gas chamber 20 b, as shown phantomlines 52 in FIG. 2. A stopper 53 may be disposed on an end position ofthe extension. The stopper 53 restricts a further movement of thepulsation suppression diaphragm 18, when the diaphragm 18 moves in adirection of expanding the liquid chamber 20 a so as to be beyond adetermined stroke A, thereby actuating the valve press rod 41. In thiscase, a stopper wall 55 (shown in FIG. 1) protrusively formed from theinside of the device body casing 17 to the gas chamber 20 b, which hasthe same object as that of the stopper 53, may be omitted.

Next, action of the pulsation damping device for a pump having the aboveconfiguration will be described.

The pressurized air fed from the pressurized air feeding device such asa compressor (not shown) is supplied to the inside of the cylindricalbody 12 of the air cylinder portion 14 via the air hole 13 b. The piston11 and the coupling member 10 are displaced in the x direction of FIG.1. As a result, the diaphragm 7 for a pump is extended in the xdirection of FIG. 1, whereby the transported liquid inside the inflowpassage 2 is sucked inside the pump working chamber 9 a via the suctioncheck valve 16 a. When the pressurized air is supplied to the inside ofthe pump operating chamber 9 b of the air cylinder portion 14 via theair hole 13 b, and is exhausted from the air hole 13 b so as to contractthe diaphragm 7 for a pump in the y direction of FIG. 1, the transportedliquid which has been sucked into the inside of the pump working chamber9 a, is discharged via the discharge check valve 16 b. Thus, thediaphragm 7 for a pump in the reciprocal pump 4 is driven via the aircylinder portion 14, so as to be deformed by extension and contraction,thereby alternately opening and closing the suction check valve 16 a andthe discharge check valve 16 b. Consequently, suction of the transportedliquid from the inflow passage 2 to the pump working chamber 9 a anddischarge of it from the inside of the pump working chamber 9 a to theoutflow passage 3 are repeated, thereby performing the predeterminedpump action. When the transported liquid is fed to the predeterminedportion by the above-mentioned action of the reciprocal pump 4, the pumpdischarge pressure causes pulsation owing to repetitions of a peak and avalley.

The transported liquid discharged from the inside of the pump workingchamber 9 a in the pump 4 via the discharge check valve 16 b is suppliedto the inside of the liquid chamber 20 a in the pulsation damping device5 via the communication passage 21. After the transported liquid istemporarily stored inside the liquid chamber 20 a, it flows in theoutflow passage 3. Then, when the discharge pressure of the transportedliquid shows the peak of a discharge pressure curve, the pulsationsuppression diaphragm 18 is extendably and contractibly deformed by thetransported liquid so as to increase the capacity of the liquid chamber20 a, thereby absorbing the pressure. At this time, a flow amount of thetransported liquid flowing out from the liquid chamber 20 a is less thanthat of the transported liquid fed from the reciprocal pump 4.

Moreover, when the discharge pressure of the transported liquid comes tothe valley portion of the discharge pressure curve, the pressure of thetransported liquid is lower than a sealing pressure of the inside of thegas chamber 20 b, which is compressed according to the extendabledeformation of the pulsation suppression diaphragm 18. Therefore, thepulsation suppression diaphragm 18 is contractibly deformed. At thistime, the flow amount of the transported liquid flowing out from theliquid chamber 20 a is more than that of the transported liquid flowingin the inside of the liquid chamber 20 a from the reciprocal pump 4. Therepeating action, i.e., the pulsation caused by the change of thecapacity of the liquid chamber 20 a is absorbed and damped.

By the way, when, in the above-mentioned action, the discharge pressurefor discharging it from the reciprocal pump 4 rises, the capacity of theliquid chamber 20 a is increased by the transported liquid so that thepulsation suppression diaphragm 18 is remarkably extendably deformed.When an amount of extendable deformation of the pulsation suppressiondiaphragm 18 exceeds a predetermined range A, the closed end portion 18b of the pulsation suppression diaphragm 18 presses the valve press rod41 in the direction of the inside of the valve chamber. As a result, thegas supply valve element 36 in the automatic gas supply valve mechanism33 is opened into the spring 37, and the high air pressure is suppliedto the gas chamber 20 b through the gas supply port 31, thereby raisingthe sealing pressure inside the gas chamber 20 b. This restricts theamount of the extendable deformation of the pulsation suppressiondiaphragm 18 so that it may not exceed the stroke A, thereby restrainingan excessive increase of the capacity of the liquid chamber 20 a. Atthis time, when the stopper 53 is disposed on the end on a side of thediaphragm, in the valve case 23, the closed end portion 18 b of thepulsation suppression diaphragm 18 abuts against the stopper 53, therebyensuring the prevention of the excessive extendable deformation of thepulsation suppression diaphragm 18. It is advantageous from a point ofview of prevention for damage thereof. The pulsation suppressiondiaphragm 18 is contracted in the direction of the standard position Sin accordance with a rise of the sealing pressure inside the gas chamber20 b. Therefore, the valve press rod 41 is distant from the closed endportion 18 b of the pulsation suppression diaphragm 18, whereby the gassupply valve element 36 return to a closing position so as to keep thesealing pressure inside the gas chamber 20 b in an adjusting state.

On the other hand, when the discharge pressure from the reciprocal pump4 is lowered, the capacity of the liquid chamber 20 a is decreased,whereby the pulsation suppression diaphragm 18 is extremely contractiblydeformed. When an amount of contractible deformation of the pulsationsuppression diaphragm 18 exceeds a predetermined range B, the slider 48of the automatic gas exhaust valve mechanism 34 is moved in thecontracting direction b of the pulsation suppression diaphragm 18 inaccordance with movement of the closed end portion 18 b of the pulsationsuppression diaphragm 18 in the contracting direction b, owing to anurging action of the spring 50 for an opening state, whereby the insideof the closed end portion 48 a of the slider 48 is engaged with theflange portion 44 of the gas exhaust valve rod 45. Thus, the gas exhaustvalve rod 45 moves in the direction b and the gas exhaust valve element43 opens the gas exhaust port 32, so that the air sealed inside the gaschamber 20 b is exhausted from the gas exhaust port 32 to theatmosphere, thereby decreasing the sealing pressure inside the gaschamber 20 b. Therefore, the amount of contractible deformation of thepulsation suppression diaphragm 18 is restricted so as not to exceed thestroke B. This prevents the capacity of the liquid chamber 20 a frombeing excessively decreased. In accordance with decrease of the sealingpressure inside the gas chamber 20 b, the pulsation suppressiondiaphragm 18 is extended to the standard position S, whereby the slider48 is pressed by the closed end portion 18 b of the pulsationsuppression diaphragm 18. As a result, while the slider 48 is moved inthe direction a, the spring 50 for an opening state is compressed, andthe gas exhaust valve element 43 closes the gas exhaust port 32 oncemore owing to the urging action of the spring 49 for a closed state.This keeps the sealing pressure inside the gas chamber 20 b in theadjusting state. As a result, in spite of fluctuation of the dischargepressure from the pump working chamber 9 a of the reciprocal pump 4, thepulsation is effectively absorbed so as to keep the range of thepulsation small.

FIG. 3 is a whole longitudinal front view of the pulsation dampingdevice for a pump, illustrating another embodiment of the presentinvention. In the embodiment, the pulsation damping device 5 as anaccumulator is independently separated from the pump, and individuallyconfigured. On a side of the lower portion of the hermetical device bodycasing 17, the liquid chamber 20 a is disposed, so that the transportedliquid fed from the pump (not shown) installed in another position issucked from the inflow passage 2 to the inside of the liquid chamber 20a, and temporarily stored therein until it discharges from the outflowpassage 3. On a side of the upper portion of the inside of the devicebody casing 17, the gas chamber 20 b is disposed. The liquid chamber 20a is separated from the gas chamber 20 b by the pulsation suppressiondiaphragm 18. The valve case 23 is fitted on the aperture 27 of theupper wall 17 b of the device body casing 17 by the bolts 24 or the likeso as to be detachably engaged therewith. The valve case 23 has the sameautomatic gas supply valve mechanism 33 and the same automatic gasexhaust valve mechanism 34 as those described in the above embodiment.Each of the pulsation damping device 5, the automatic gas supply valvemechanism 33 and the automatic gas exhaust valve mechanism 34 has thesame configuration and action as those of the preceding embodiment.Therefore, the description thereof is omitted.

INDUSTRIAL APPLICABILITY

The invention according to claim 1 makes it possible to absorb and dampthe pulsation of the reciprocal pump, and to keep increase or decreaseof the capacity of the liquid chamber within a predetermined range, bymeans of a pressure balance between the liquid pressure and the gaspressure, and effectively absorb the pulsation, thereby keeping therange of pulsation small. Moreover, the present device can be installedin any attitude, namely either horizontally or vertically.

The invention according to claim 2 makes it easy to perform maintenanceof each of the gas supply valve and the gas exhaust valve, and thestructure thereof is so simple that it is economically produced.

According to the invention of claim 3, the reciprocal pump is integratedwith the pulsation damping device, thereby downsizing a whole of thedevice, and attaining greatly reduction of the installation space.

According to the invention of claim 4, the excessive extendabledeformation is suppressed, thereby preventing damage of the pulsationsuppression diaphragm.

What is claimed is:
 1. A pulsation damping device for a pump,comprising: a hermetical device body casing having a liquid chamber forsupplying a transported liquid to be transported by a reciprocal pumpfrom an inflow passage, temporarily storing the transported liquid, anddischarging it to an outflow passage, and a gas chamber to be filledwith a gas for suppressing pulsation, a pulsation suppression diaphragmfor suppressing pulsation, which partitions an interior of said devicebody casing into the liquid chamber and the gas chamber, and which canfreely reciprocate according to a balance between each fluctuation offlowing amount and pressure of the transported liquid and a gas sealingpressure inside the gas chamber, a gas pressure supply means forsupplying the gas chamber with a gas pressure, a gas supply port forguiding the gas pressure from the gas pressure supply means to an insideof the gas chamber when the gas sealing pressure inside the gas chamberis raised, a gas exhaust port for exhausting the gas from the gaschamber to the outside thereof when the gas sealing pressure inside thegas chamber is lowered, an automatic gas supply valve mechanism forusually closing the gas supply port, an automatic gas exhaust valvemechanism for usually closing the gas exhaust port, a valve press roddisposed between the automatic gas supply valve mechanism and thepulsation suppression diaphragm, which is actuated so as to open usuallythe gas supply port when the pulsation suppression diaphragm is movedbeyond a predetermined stroke in the direction of expanding the liquidchamber, and a slider disposed between the automatic gas exhaust valvemechanism and the pulsation suppression diaphragm, which is actuated soas to open usually the gas exhaust port when the pulsation suppressiondiaphragm is moved beyond a predetermined stroke in the direction ofreducing the liquid chamber, wherein the automatic gas exhaust valvemechanism includes: a gas exhaust valve rod loosely inserted in athrough hole of a spring receiving member fixed in the device bodycasing, so as to form a space, a gas exhaust valve element disposed on atip of the gas exhaust valve rod, which can freely touch or separatefrom a valve seat of the gas exhaust port, and the slider arranged at arear end of the gas exhaust valve rod so as to be slidable in an axialdirection of the valve, a spring for a closing state is disposed betweenthe gas exhaust valve element and the spring receiving member, and aspring for an opening state is disposed between the gas exhaust valveelement and the slider.
 2. A pulsation damping device for a pump,according to claim 1, wherein the device body casing is provided with anaperture for communicating with the gas chamber, and a valve case isdetachably engaged with an inside of the aperture, the valve case isprovided with the gas supply port, the gas exhaust port, the automaticgas supply valve mechanism, the valve press rod, the slider, the gasexhaust valve element of the automatic gas exhaust valve mechanism, theexhaust valve rod, the spring receiving member, the spring for a closingstate, and the spring for an opening state.
 3. A pulsation dampingdevice for a pump, according to claim 1, wherein the device body casingis integrally provided with an air-driving type reciprocal pump, theair-driving type reciprocal pump includes a diaphragm for a pump, whichis extendably and contractibly deformed in an extending and contractingdirection of the pulsation suppression diaphragm, an air cylinderportion for driving the diaphragm for a pump so as to be extendably andcontractibly deformed, and a pump working chamber disposed inside thediaphragm for a pump, the pump working chamber having suction anddischarge check valves for sucking and discharging the transportedliquid, the check valves being alternately opened and closed inaccordance with extendable and contractible deformation of the diaphragmfor a pump, and the transported liquid discharged from the pump workingchamber via a discharge check valve is f edto the liquid chamber.
 4. Apulsation damping device for a pump, according to claim 2, wherein astopper is disposed on an end on a side of the gas chamber in the valvecase, and the stopper restricts further movement of the pulsationsuppression diaphragm when the pulsation suppression diaphragm moves inthe direction of expanding the liquid chamber so as to be beyond apredetermined stroke and the valve press rod is actuated.